Fran and All,
It seems that you were trying to find info on glutamate within the heart, and although there's not much about this specific info, I thought you would find this study of interest.
The Glutamate Receptor Ion Channels
[
pharmrev.aspetjournals.org]
This was also very interesting as it pertains to acetylcholine and nicotinic and muscarinic receptors.
Fine Tuning of Sympathetic Transmitter Release via Ionotropic and Metabotropic Presynaptic Receptors
[
pharmrev.aspetjournals.org]
There is so much info at this link, I can't even begin to get through just reading the topics of research, but it's a good one.
Richard